1. Field of the Invention.
The present invention relates to syringes and more particularly concerns syringe assemblies capable of spraying liquid.
2. Description of Related Information.
Many injectable medications are packaged and distributed in hypodermic syringes that will eventually be used to administer the medication to the patient. Prefilled syringes are available from pharmaceutical manufacturers, and syringes are frequently prefilled in hospital pharmacies. In both instances, the prefilled syringe is subject to a variety of environmental challenges due to storage, shipping and/or handling before medication is administered to the patient. Accordingly, the contents of the syringe must be sealed to preserve their stability and/or sterility.
In some medical procedures, it is necessary or desirable to apply therapeutic liquids to a wound or surgical site by spraying the liquid onto the affected area. It is also sometimes desirable to administer the therapeutic liquid spray to the eye, ear, nose or throat of a patient rather than delivering the therapeutic liquid though a hypodermic needle. A growing area of activity involves the spraying of therapeutic liquids into the nasal cavity of a patient. This delivery route eliminates the need for puncturing the patient's skin with a sharp hypodermic needle and eliminates the possibility of other health care workers being exposed to a sharp non-sterile or contaminated hypodermic needle.
The syringe is the low cost, efficient, sterile instrument of choice for delivering liquid medication through a hypodermic needle. The hypodermic syringe can also be an excellent storage device for medication placed in it by a pharmaceutical manufacturer or hospital pharmacy. The delivery of therapeutic liquid via spray, through the nasal passageway, is a preferred method for the delivery of certain therapeutic liquids under certain conditions.
The art has not taught a device for the intranasal delivery of therapeutic liquid which incorporates the significant cost, performance and storage advantages of a prefilled hypodermic syringe. For example, U.S. Pat. Nos. 3,874,380 and 3,874,381 to Baum teach a dual nozzle intranasal delivery device which uses a hypodermic syringe in a very complicated set up involving a medication vial and a hypodermic needle and complex passageways for converting a stream of liquid from a hypodermic syringe into two separate passages leading to adjacent parallel spray nozzles.
U.S. Pat. No. 3,502,078 to Hill et al. teaches a dual-tipped nasal syringe and aspirating device which includes dual syringe bulbs connected to parallel tubes leading to dual nostril engaging tips. Although the device of Hill et al. appears to be costly to manufacture and may have shortcomings with respect to its capability to delivering all of the medication contained therein, it does offer an advantage over Baum's device in that both nostrils will receive no more than the amount of liquid medication in each side of the device. Accordingly, an equal dose volume can be delivered to each nostril.
U.S. Pat. No. 4,923,448 to Ennis, III teaches a syringe with spray nozzle tip for discharging the liquid contents of the syringe in a spray. The syringe of Ennis, III is an improvement over prior art devices in that it attempts to combine the efficiency of a syringe with a spray nozzle. However, the syringe of Ennis, III due to its structure cannot be used to store medication and should be filled at the time of use. It appears that medication in the barrel of the Ennis, III syringe can drain out of the spray aperture since no structure either blocks this possible flow or protects the device from outside contaminants. Providing a protection cap over the tip of the Ennis, III syringe would apparently still allow an amount of the liquid to pass through the aperture into the protective cap where it cannot be delivered to the patient. A similar syringe device is taught by Wolf et al. in U.S. Pat. No. 4,767,416 except the spray nozzle of Wolf et. al. is a separate attachment which may be added to the syringe at the time of use. Accordingly, the syringe may be used as a storage device. However, the use of such a device requires additional components, procedures and opportunities for contamination and additional cost because the syringe must be assembled with the sprayer at the time of use. The assembly of the syringe of Wolf can also present a safety problem because the locking luer tip of the syringe can readily accept a hypodermic needle and allow injection of a medication formulated for spray application only. Also, neither Wolf et al. nor Ennis, III provide any structure to control the amount of medication delivered to each nostril. If it is preferable to split the dose between the nostrils the operator of these syringes must rely on guess work or volume measuring indicia on the syringe barrel if such indicia exists.
European Patent Application No. 0 334 349 teaches a device for a dosage dispensing of a liquid medicine which provides structure for controlling the dose so that equal or predetermined amounts may be delivered with each stroke of the syringe. However, the device of the '349 patent application is extremely complex and involves covering structure over the syringe which appears to be substantially more expensive and difficult to assemble, fill and use.
The prior art also includes commercially available over-the-counter nose drop spray pump and reservoir assemblies. In use these devices have a spray tip which is placed in the nostril and the pump is manually cycled to deliver medication. These devices are not suitable for many forms of therapy because the dose cannot be accurately controlled at the reservoir which may contain 20 or more doses that could be delivered at one time. Accordingly, these spray pump/reservoirs can be dangerous because of their ability to deliver substantial overdoses.
While the art has recognized the use of hypodermic syringes for the efficient storage and delivery of liquid medication and that the preferred delivery of some medications in the form of a spray to areas of the body such as the nasal cavity, there is still a need for a simple prefillable medication delivery device which combines all of the delivery and storage advantages of a hypodermic syringe with the ability to deliver medication in the form of a spray without complex adapters or assembly procedures at the time of use wherein said delivery device can include single use features to help prevent refilling and reuse. In the case of nasal sprayers there is also a need to control the amount of medication delivered to each nostril and to assure that only a single dose would be delivered.